In recent years, touch panels, and display panels and display devices with a touch function, have been increasingly popular as they become friendly, convenient and prompt to operate. The touch panels can be categorized by their different operation principles into, for example, a resistive-type touch panel, a capacitive-type touch panel, an electromagnetic inductive-type touch panel, etc. Particularly the resistive touch panel and the capacitive touch panel are advantageous in their possibility of being operated directly with a hand or finger. However it may be difficult to distinguish touching by the hand or finger from touching by a stylus while writing with the stylus because the hand or finger is generally placed on the touch panel. The electromagnetic inductive touch panel generally includes a plurality of electromagnetic inductive coils or antennas arranged in the X and Y direction and a positioning device (e.g., an electromagnetic stylus). The position of the electromagnetic stylus can be determined accurately by the electromagnetic inductive touch panel even if the hand or finger is placed on the touch panel.
FIG. 1a is a schematic diagram of an electromagnetic inductive touch panel structure in the prior art. As shown in FIG. 1a, the electromagnetic inductive touch panel includes first coils 11 (including 11-1, 11-2, 11-3 . . . 11-48) arranged in the X direction and extending in the Y direction and second coils 12 (including 12-1, 12-2, 12-3 . . . 12-48) arranged in the Y direction and extending in the X direction, where typically the first coils 11 intersect with and are insulated from the second coils 12, and both the first coils 11 and the second coils 12 are arranged on a substrate (not illustrated). A drive detection method of the touch panel in the prior art will be described with reference to FIG. 1b and FIG. 1c taking the first coils 11 as an example. A drive signal is applied to the respective coils among the first coils 11, and the respective coils emit an electromagnetic signal and then receive an electromagnetic signal (referred to as a reflected signal) reflected by an electromagnetic stylus and generate an inductive signal. Specifically a drive signal is applied to the first coil 11-1 so that the first coil 11-1 emits an electromagnetic signal, and the electromagnetic stylus receives the electromagnetic signal emitted from the first coil 11-1, and a resonant circuit (e.g., an LC resonant circuit) therein resonates to generate and emit an electromagnetic signal (i.e., a reflected signal) at the same frequency as the electromagnetic signal emitted by the first coil 11-1, and the first coil 11-1 receives the electromagnetic signal reflected by the electromagnetic stylus and then generates an inductive signal (which is typically embodied as an inductive voltage); and alike all the first coils 11-2, 11-3, . . . , 11-48 generate inductive signals, thus resulting in 48 inductive signals in total. Function fitting (e.g., quadratic function fitting) is performed on these 48 inductive signals, and the position (Xp) of the peak of fitted curve is determined as the coordinate of a touch position of the electromagnetic stylus in the X direction. The coordinate of a touch position of the electromagnetic stylus in the Y direction can be determined similarly.
Although the touch position of the electromagnetic stylus can be well determined in the touch panel and drive detection method thereof described above, it is desirable to improve the efficiency of drive detection thereof.